1. Field of the Invention
The present invention relates to a separation distance derivation system for derivation of a separation distance between objects, and to a thickness gauge that is inserted between the objects.
2. Description of the Related Art
In some instances, the separation distance of gaps that arise, or that are intentionally provided, between objects in structures and machinery and equipment, is measured, with high precision and at a high resolution of 0.01 mm. However, in some instances it is not possible to simply use a distance-measuring tool such as a caliper or the like if the separation distance of a gap to be measured is narrow.
In capacitive GAP measuring instruments, for instance, separation distances can be obtained by inserting a thin sheet-like probe into a gap between objects, causing current to flow between the objects and an electrode (probe), and measuring the voltage at that time. However, accurate separation distances have been difficult to obtain using such measuring instruments in cases where, for instance, the thickness of the probe and the position of the probe between objects, among other parameters, are subjected to numerous limitations, or instances where objects are not conductors, for instance in the case of carbon-fiber reinforced plastic (CFRP).
A technology has been disclosed (for instance, in Japanese Unexamined Patent Application Publication No. H8-304061), in which the leading end of a guide bar is shaped in the form of a wedge, and the latter is inserted into a gap between objects, such that the separation distance is obtained on the basis of the insertion length at which the wedge moves no further. This technology does not depend on the material of the objects; however, the technology allows only measuring the separation distance of the opening (inlet) of the gap between the objects. The measurement result was in some instances different from the substantial separation distance between opposing planes in the gap.
Therefore, thickness gauges are used that allow obtaining the substantial separation distance of the gap between the objects, without limitation on the material of the objects, in cases where a separation distance is to be measured with high resolution and high precision (for instance, Japanese Unexamined Utility Model (Registration) Application Publication No. S64-34501). In such a thickness gauge, the separation distance can be obtained by inserting a plurality of plate-like blades, of known thickness, between objects, and by summating then the thicknesses of the plurality of inserted blades. Another known technology for preventing human error involves measuring the separation distance all at once, using a caliper, with the blades inserted in the gap, instead of through summation of the thicknesses of the plurality of blades.
In the above-described technology that utilizes concomitantly a thickness gauge and a caliper, a number of blades in a plurality of bundled blades, as the thickness gauge, are selectively inserted between the objects, and hence alternate blades are selected, i.e. first blade, fifth blade and ninth blade, depending on the separation distance between the objects. Therefore, when the caliper was applied, with the blades inserted in the gap, a concern arose in that the caliper might derive a separation distance that was greater than the actual separation distance in proportion to a gap that may arise between the inserted blades at sites other than the insertion portion.